Add NATS account-balance SoT and statement review for customers, CS, and sales

Internal billing now uses verae.billing.* request-reply and pubs. zappier-account-balance tracks prepaid, credits, usage, and payments. Portal, admin, CS, and sales all review the same statement. Independent Forgejo repos stay split via push-module-repos.

packages/zappier/src/statement.ts

@@ -0,0 +1,38 @@
+import { CreditAdjustment } from './credits';
+import { Invoice } from './invoicing';
+import { UsageEntry } from './usage';
+
+export function composeStatement(args: {
+  customerId: string;
+  prepaidCents: number;
+  credits: CreditAdjustment[];
+  usage: UsageEntry[];
+  invoices: Invoice[];
+}) {
+  const payments = args.invoices
+    .filter((i) => i.customerId === args.customerId && (i.status === 'paid' || i.status === 'issued'))
+    .map((i) => ({
+      id: i.id,
+      customerId: i.customerId,
+      cents: i.billableCents,
+      kind: i.status === 'paid' ? 'invoice-paid' : 'invoice-issued',
+      reason: i.period,
+      at: new Date(i.paidAtMs || i.issuedAtMs || Date.now()).toISOString(),
+    }));
+  return {
+    customerId: args.customerId,
+    prepaidCents: args.prepaidCents,
+    credits: args.credits.filter((c) => c.customerId === args.customerId),
+    usage: args.usage
+      .filter((u) => u.customerId === args.customerId)
+      .slice(-50)
+      .reverse()
+      .map((u) => ({
+        customerId: u.customerId,
+        endpointId: u.endpointId,
+        cents: u.cents,
+        at: u.timestamp.toISOString(),
+      })),
+    payments,
+  };
+}